Abstract P3-17-09: Resolution of DCIS in patients with early breast cancer receiving primary chemotherapy for invasive breast cancer

Abstract

Abstract Background Ductal Carcinoma in Situ (DCIS) plays a pivotal role in surgical planning for patients who are to undertake primary chemotherapy. As DCIS is not thought to be responsive to chemotherapy, many women with large primaries or extensive DCIS on initial diagnosis will be planned for and undergo mastectomy. To investigate the role of chemotherapy in invasive breast cancer with concomitant ductal carcinoma in situ (DCIS), we examined patients who had primary systemic therapy for a primary invasive cancer with either radiologically or histologically proven DCIS to see if there were patients in whom there was no evidence of DCIS at resection. Methods This was a retrospective single centre study. Examining the records of all patients who had received primary chemotherapy between January 2010 and October 2014. Patients were identified through the Guy's breast cancer database and chemotherapy prescribing system. To fully assess the DCIS status, all patients were cross-referenced with the electronic notes on our electronic noting system (MOSAIQ), radiology on Patient Archiving and Communication System (PACS) and histology on our Electronic Patient Record (EPR). Results 1526 patients were identified, of whom 156 underwent primary chemotherapy. Of these, 46 patients had a pre-chemotherapy biopsy confirming DCIS, of whom 30 also had radiological evidence of DCIS. A further 26 had micro-calcification on their initial imaging which was presumed to be DCIS. Twelve of the 46 patients with biopsy proven DCIS at presentation did not have DCIS at resection. Of these 9 had a mastectomy, with 5 achieving a pathological complete response (pCR), of whom 4 had a complete radiological response (rCR). Of the 26 who had micro-calcification pre-chemotherapy, 15 did not have DCIS in the resection specimen. Of these, 10 had a mastectomy, with 6 having a pCR of whom 3 also had rCR. Conclusion This retrospective study suggests that chemotherapy can influence DCIS, with 12 biopsy proven having a pCR post treatment. This may indicate that some patients may be spared mastectomy. Although there were patients with radiological evidence of DCIS, without a confirmatory biopsy we cannot be sure that these were malignant. This highlights the need to ensure that all suspicious areas distant from the primary tumour should be biopsied before treatment. In conclusion, for patients who have an excellent clinical and radiological response, even in the presence of DCIS at presentation, more intensive evaluation is indicated if conservative surgery is a possibility. Citation Format: Chowdhury MHR, Thillai K, Lucey A, Michalarea V, Mera A, Karapanagiotou E, Sandri I, Mansi J. Resolution of DCIS in patients with early breast cancer receiving primary chemotherapy for invasive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-17-09.